This invention relates to a pyrochemical process for converting spent oxide nuclear fuel from a light water reactor to metal and for separating plutonium and higher actinide metals such as americium, neptunium and curium from the bulk uranium. Because the end product is for use in a integrated fast reactor (IFR), high decontamination of the separate streams from fission products is not a prime concern nor is the total separation of plutonium americium, neptunium and curium (hereinafter transuranic elements) from the bulk uranium. The transuranic elements will be used to make core fuel for a liquid metal fast breeder (LMFBR) particularly of the new IFR or integrated fast reactor type. Because of the purpose for which this reprocessed fuel will be used, some uranium can accompany the plutonium stream since the uranium to plutonium ratio in a LMFBR fuel is in the range of 2-3.5:1. The bulk uranium or uranium rich product stream is to be stored for later use, for instance as a uranium source for breeder blankets in a liquid metal fast breeder reactor (LMFBR), when and if such fast reactors are commercially viable. A goal of the process is to remove approximately 90% of the transuranic actinides from the uranium so that the transuranic actinides can be used as core fuel and the remaining uranium can be used as blanket material.
Accordingly, it is an object of the invention to provide a process for separating transuranic or transuranium actinide values from spent oxide nuclear fuel while reducing the amount of nuclear waste material which has to be treated and stored.
Another object of the invention is to provide a process using various combinations of alloys and molten salts selectively to separate uranium from the transuranic values present in spent nuclear oxide fuel and to reuse the alloys and the salts several times in order efficiently to separate the desired values while producing a very small amount of nuclear waste.
A still further object of the invention is to provide a process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels containing rare earth and noble metal fission products as well as other fission products, comprising reducing the oxide fuel with Ca metal in the presence of Ca halide and a molten Cu--Mg alloy to precipitate uranium metal and some of the noble metal fission products leaving the Cu--Mg alloy having transuranium actinide metals and rare earth fission product metals and some of the noble metal fission products dissolved therein and leaving Ca halide having fission products of alkali metals and the alkali earth metals and iodine dissolved therein, separating the Ca halide and the fission products contained therein from the uranium metal and Cu--Mg alloy, oxidizing any Ca metal present in the Cu--Mg alloy to the halide and separating same from the Cu--Mg alloy, contacting the Cu--Mg alloy having transuranium metals and rare earth fission product metals and the noble metal fission products dissolved therein with a transport salt including Mg halide to transfer Mg values from the transport salt to the Cu--Mg alloy while transuranium actinide and rare earth fission product metals transfer from the Cu--Mg alloy to the transport salt, contacting the transport salt having the transuranium actinide and rare earth fission product values dissolved therein with a Mg-containing alloy to transfer Mg values from the alloy to the transport salt while the transuranium actinide and rare earth fission product values dissolved in the salt are reduced and transferred to the Mg-containing alloy, whereby an alloy is formed having transuranium actinide and rare earth fission product values therein while precipitated uranium values along with precipitated noble metal fission product metals are available for separation from the Cu--Mg alloy.
The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.